The launch of the Federal Building the Education Revolution (BER) prompted Candlebark School principal, author John Marsden, to build a new library. With the school located in a designated bushfire prone area at the edge of a tall forest, the new library building is also intended to serve as a fire refuge of last resort. The solution was an earth-covered timber construction, built into the side of a hill, preserving views from the school dining hub above to the open valley below.
DESIGN DESCRIPTION
Sustainably sourced timbers and engineered wood products are used throughout the project and have been applied with elegance to address a massive structural challenge of supporting the earth laden roof.
Despite initial advice from the structural engineer that such roof loads, effectively 2.5 tonnes per square metre, need to be carried by concrete and/or steel structures, the architect held with some stubbornness to the dream of an all timber roof frame because of the carbon sequestered in it from the atmosphere, its easy workability and potential aesthetics.
The massive post and beam portals used could be fabricated by carpenters off-site in seasoned pine laminated veneer lumber.
The library sits on a concrete slab that lies 4.5 metres below natural ground at its northern edge and meets natural ground level at its southern edge. The external retaining wall, of 290mm thick core reinforced concrete block construction, is curved to a full half circle. This shape provides considerable restraint against the horizontal load of retained earth. The south wall is curved to broader radius, and consists mainly of tall counter-balanced double hung windows and glazed doors that open to intimate courtyards, open terrace and the valleys beyond.
Internally, the timber portal frames are exposed forming a visually dramatic gently barrelled fan-like structure. The underside of purlins between these portals is lined with Hoop Pine plywood sourced from sustainable plantations in Queensland.
Windows and external doors are framed in select recycled Blackbutt (Eucalyptus pilularis), a dense, durable and highly fire resistant hardwood. The chunky pergola embracing the south terrace is constructed from salvaged Monterey Cypress (Cupressus macrocarpa).
Waterproofing and perimeter drainage for the earth-covered building had to be of high quality both as a material system and in its installation detailing. After much research and liaison with prospective installation contractors, a composite system was selected that represented a significant portion (about 10 per cent) of the total construction cost.
In terms of air quality, the library has a three-stage ventilation strategy. Firstly, fresh air is readily accessed by the opening of the counter-balanced double-hung windows in the south window wall. Secondly, if the outdoor air is very still, further natural cross and stack ventilation can be activated by opening electrically controlled butterfly dampers just below the head of large concrete vent shafts, which in turn extend up from the ceiling in the rear northern part of the building through the earth roof cover. Finally, if the thermally massive building interior gathers heat through high occupancy on a hot day, the windows, but not the roof vent shafts, are closed and mechanical fans built into concealed wall plenums can be switched on overnight. These fans flush cool mountain air through the interior to purge it of heat absorbed through the day.
The modular book shelving in the library is a hybrid system of custom made timber shelving and proprietary steel racking components. Rather than opting for proprietary powder-coated all-steel systems commonly found in school and public libraries, the shelves themselves were fabricated by a local cabinetmaker using Hoop Pine plywood. These modular timber shelves were then simply attached to proprietary steel racking, whether wall mounted or freestanding as mobile trolleys. This hybrid was found to be more robust and serviceable than the proprietary all-steel alternative, less expensive, and more attractive in this architectural setting.
The interior of the library is intentionally unconventionally relaxed, eclectically furnished with acquisitions including circular pods of rattan chairs, a large antique medicine cabinet, an aisle of old movie house chairs, and a Russian WW2 motorbike for the boys to lounge and read on. "It's no different to having a shelf of books in a motorbike shop" is Marsden's justification.
ACCOLADES
Australian Timber Design Awards Overall Winner 2012
Australian Timber Design Awards Best Public or Commercial Building 2012
Australian Timber Design Awards Best in Southern Region of Australia 2012
Australian Timber Design Awards Best Use of Engineered Timber Products 2012
Australian Timber Design Awards Geoffrey Sanderson Perpetual Trophy 2012
Australian Timber Design Awards People's Choice Award 2012
PRODUCTS
REAR EXTERNAL EARTH RETAINING WALLS
ADBRI MASONRY, 290 THICK STEEL-REINFORCED CORE-FILLED CONCRETE BLOCKWORK
INTERNAL WALLS
ADBRI MASONRY, 190 THICK STEEL-REINFORCED CORE-FILLED CONCRETE BLOCKWORK
TIMBER PORTAL FRAME
WESBEAM, E-BEAM +F17 LAMINATED VENEER LUMBER IN PINUS PINASTER MARITIME PINE
TIMBER ROOF PURLINS
RIPPED OFFCUT EX SHAPING OF TIMBER PORTAL FRAMES
STRUCTURAL ROOF SHEET
CARTER HOLT HARVEY, ECOPLY 25 THICK F11 EXTERIOR GRADE CD FACE A-BOND (LOW EO) RADIATA PINE PLYWOOD (TREATED TO H3)
DRAINAGE CELL FOR EARTH COVERED ROOF
ELMICH, VERSIFLEX 30 THICK RECYCLED POLYPROPYLENE DRAINAGE CELL
WATERPROOFING FOR EARTH COVERED ROOF
HENKELL COSMOFIN 1.5 THICK REINFORCED PVC SHEET MEMBRANE
DRAINAGE CELL FOR EARTH RETAINING WALLS
ATLANTIS, FLOCELL 30 THICK RECYCLED POLYPROPYLENE DRAINAGE CELL
WATERPROOFING FOR EARTH RETAINING WALLS
FLEXASEAL, SYSTEM TSW-L REINFORCED LATEX MODIFIED COMPOSITE TANKING SYSTEM
WALL INSULATION
ISOBOARD, VVH 75 THICK EXPANDED POLYSTYRENE SHEET
ROOF INSULATION 140
THICK R3.0 POLYESTER BATT
CURVED SOUTH WALL CLADDING BGC
DURACOM 9 THICK COMPRESSED FIBRE CEMENT SHEET
WINDOWS & EXTERNAL DOORS
MOULDRIGHT JOINERY, SELECT RECYCLED EUCALYPTUS PILULARIS (BLACKBUTT)
INSECT AND EMBER SCREENS
BENT IRONWORK CUSTOM MADE IN STAINLESS STEEL
